Endoscopy is a diagnostic and medical procedure which allows to examine the interior of a hollow organ or cavity of the body by means of an instrument called endoscope, without employing invasive surgery. Endoscopy is commonly used for diagnostic purposes, even though minor, non-invasive surgical and non-surgical interventions can be performed during an endoscopic procedure. Typically, said minor interventions comprise cauterization of a bleeding vessel, widening a narrow esophagus, removing polyps, adenomas and small tumors, performing biopsies or removing a foreign object. Endoscopy is used by specialists to examine, for example, the gastrointestinal tract, the respiratory tract, the ear, the urinary tract, the female reproductive system and, through small incisions, normally closed body cavities such as the abdominal or pelvic cavity (laparoscopy), the interior of a joint (arthroscopy) and organs of the chest (thoracoscopy and mediastinoscopy). The endoscope is an illuminated usually optic fiber flexible or rigid tubular instrument for visualizing the interior of a hollow organ or part (as the bladder, esophagus, stomach or intestine) for diagnostic or therapeutic purposes, that typically has one or more working channels to enable passage of instruments (such as forceps, elettrosurgical knife, endoscopic injection needles or scissors) or to facilitate the removal of bioptic samples. It includes a suitable lamp and imaging device at its distal portion, and it can be inserted through natural occurring openings of the body, such as the mouth, the anus, the ear, the nose or through small surgical incisions. Given the wide variety of body organs or cavities which can be examined by means of endoscopic procedures, several types of endoscopes exist, such as, for example, laryngoscope, thoracoscope, angioscope, colonoscope, enteroscope, sigmoidoscope, rectoscope, proctoscope, anoscope, arthroscope, rhinoscope, laparoscope, hysteroscope, encephaloscope, nephroscope, esophagoscope, bronchoscope, gastroscope, amnioscope, cystoscope.
In particular, endoscopic procedures are widely applied in the gastrointestinal tract, both for diagnostic purposes and for small interventions. With the progress advance of the imaging technology, endoscopic procedures can be used to accurately examine the mucosa that covers the gastrointestinal cavities, and to detect small and large pathological lesions, such as inflammatory tissue, polyps, pseudo-polyps, serrated lesions, adenomas, ulcerations, dysplasias, pre-neoplastic and neoplastic formations, tumors and similar. In addition, endoscopic procedures in the gastrointestinal tract allow the doctor to perform minor, surgical or non-surgical interventions, which comprise, for example, biopsies and removal of pathologic lesions (polyps, adenomas, dysplasias, Barrett's dysplasia, pre-neoplastic and neoplastic formations, tumors). Surgical interventions include two endoscopic resection procedures commonly used in gastrointestinal endoscopy to remove pathological lesions: endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD). These two techniques have provided new alternatives for minimally invasive treatment of gastrointestinal polyps, adenomas, dysplasias, Barrett's dysplasia and early-stage cancers that involve a minimum risk of lymph-node metastasis. EMR is an endoscopic technique developed for removal of sessile or flat neoplasms confined to the superficial layers (mucosa and submucosa) of the GI tract. EMR is typically used for removal of lesions smaller than 2 cm or piecemeal removal of larger lesions. EMR also plays an important role in the assessment of resected specimens for accurate pathological staging. In contrast to polypectomy, EMR involves the lifting up of a lesion from the muscular layer by injecting a fluid agent, commonly normal saline (NS) solution, into the submucosal layer. EMR is also useful for obtaining specimens for accurate histopathological staging to determine the risk of lymph-node metastasis. EMR facilitates the complete removal of the affected mucosa by excising through the middle or deeper portion of the gut wall submucosa. Various EMR techniques have been described and four methods involving snare resection are commonly used: (1) the inject and cut method; (2) the inject, lift, and cut method; (3) cap-assisted EMR (EMRC); and (4) EMR with ligation (EMRL). The inject and cut technique, also known as submucosal injection polypectomy, has become widely used in recent years because of its simplicity. The diseased mucosa is lifted up from the muscular layer by creating a submucosal fluid cushion, captured, strangulated using an electrosurgical snare, and then resected. However, injection into the thin submucosal layer is a delicate process, the injected solution tends to dissipate quickly, flat and depressed lesions are hard to capture with the snare compared with protruded lesions, and large or awkwardly located lesions can be difficult to remove (Uraoka et al., Drug Design, Development and Therapy 2008:2 131-138). Injection-assisted EMR is frequently used for large flat colon polyps.
Endoscopic submucosal dissection (ESD), a relatively new endoscopic resection procedure, was specifically developed for removing larger lesions. Lesions are dissected directly along the submucosal layer using an electrosurgical knife, resulting in an en-bloc resection of even large lesions. ESD has been predicted to replace conventional surgery in treating certain cancerous stages, but since it has a higher rate of perforation and bleeding complications than conventional EMR, a greater degree of endoscopic skill and experience is required than for EMR. Various submucosal injection solutions had previously been developed and shown to be satisfactory for use during EMR, but introduction of the lengthier ESD procedure required a longer-lasting solution to help identifying the cutting line during dissection of the submucosal layer (Uraoka et al., Drug Design, Development and Therapy 2008:2 131-138).
The use of submucosal injection is essential for a successful EMR, as injection of fluid into the submucosa cushions facilitates the isolation of the tissue to be removed just before capture of the target lesion with a snare, thereby reducing thermal injury and the risk of perforation and haemorrhage while also facilitating an en-bloc resection. Submucosal injection is considered to play an important role in the EMR procedure, and the “ideal” submucosal injection solution should be both long-lasting as regards cushion duration and capable of producing a hemispheric shape to facilitate snaring. In addition, providing a sufficiently high submucosal elevation is important for safe submucosal cutting during the ESD procedure (Uraoka et al., Drug Design, Development and Therapy 2008:2 131-138).
The ideal solution for injection-assisted EMR should be safe, inexpensive, non toxic, readily available, easy to inject and especially it should be capable of providing a high, long-lasting submucosal cushion. Wound healing characteristics should be also requested to facilitate the closure of the wound created by the removal of the resected mucosa, as well as the presence of a colouring agent (such as a dye) to allow an improvement in distinguishing more easily the deepness of the muscolaris mucosa, avoiding undue perforation during ESD.
Normal saline solution (NS) has been commonly used for this purpose, but it is difficult to produce the proper submucosal fluid cushion and maintain the desired height, particularly for flat elevated lesions, because of the rapid dispersion of the solution through the mucosal layers and absorption of NS into the surrounding tissue (Uraoka et al., Drug Design, Development and Therapy 2008:2 131-138). For this reason, in long-lasting procedures and in the removal of large lesions, such as large flat polyps, repeated injection of the solution into the submucosal layer are required, with a consequent operational complication for the personnel of the endoscopic unit.
In order to overcome the fast disappearance of the cushion, which represents a typical problem encountered with NS, during the past decade several types of solutions have been described and tested for the use in solution-assisted EMR. Each type of solution has its advantages and disadvantages. For example, hyaluronic acid (HA) solutions have been reported as the best agents for submucosal injections. HA solutions provide long-lasting fluid cushions and allow high successful en-bloc resections and low perforation complication rates. Moreover, HA is safe, biocompatible and non-toxic, since it is a physiological component of the extracellular matrix. The main disadvantage of HA is its high cost, which renders it quite inaccessible for most endoscopic units. Other solutions have been tested and described, such hypertonic dextrose and hydroxypropyl methylcellulose (HPMC), which however have been reported to cause tissue damage and inflammation. Another recently investigated injection solution is fibrinogen mixture (FM) solution, which has a high viscosity and produces a long-lasting submucosal elevation, thus lowering the number of injections per lesion and shortening procedure times; in addition, FM is inexpensive. The main disadvantage of FM is the possible the risk of transmission of viruses: since FM is obtained by the fractionalization of coagulation proteins in human serum, contamination with hepatitis or other viruses is possible. As above illustrated, an ideal solution for EMR and ESD has not yet been developed, and many researches in this field are still on-going.
Ideally, viscous solutions such as HA solutions or HPMC solutions could meet the requirements of the endoscopic resection procedures, since they could provide a high and long-lasting cushion because of the low tendency of the water cohordinated by these polymers to diffuse and spread out in the tissues surrounding the lesion. However, the use of viscous solutions, such as HA solutions or HPMC solutions, poses some challenges in the procedure, due to the difficulty to get a viscous solution flowed through the injection devices. As a matter of facts, in gastrointestinal EMR and ESD procedures, the injections of the cushion-forming solutions are performed using endoscopic injection needles. As well known in the art, endoscopic injection needles are devices which can be long up to about 230 cm and which include a relatively long catheter within which an inner injection tube having a distal injection needle is slideably disposed. A proximal actuating handle is coupled to the catheter and the injection tube for moving one relative to the other when necessary. Fluid access to the injection tube is typically provided via a luer connector on the handle. Endoscopic injection needle devices are typically delivered to the injection site through the working channel of the endoscope. In order to protect the lumen of the endoscope working channel from damage, the handle of the infusion needle device is manipulated to withdraw the distal injection needle into the lumen of the catheter before inserting the device into the endoscope. This is important to prevent exposure of the sharp point of the injection needle as the device is moved through the lumen of the endoscope. When the distal end of the endoscopic injection needle device is located at the injection site, its handle is again manipulated to move the injection needle distally out of the lumen of the catheter. When advanced to the most distal position, the exposed portion of the injection needle is approximately 4-6 mm in length. After the injection site has been pierced, the solution, usually contained in a 5 mL to 10 mL syringe provided with a luer-lock fitting connected to the handle of the injection needle, is delivered through the injection tube and the needle into the injection site.
The injection needle and other accessories commonly used during endoscopic procedures, such as snares for polypectomy, clipping devices, biopsy forceps and similar, are passed through one or more specific channels of the endoscope, usually called working channels or operating channels. Depending upon the type of endoscope used in GI endoscopy (e.g. gastroscope, enteroscope, colonoscope, duodenoscope, sigmoidoscope and similar), the inner diameter of the working channels may vary considerably. However, the most common endoscopes used in GI endoscopy have working channels with inner diameter in the range from about 2 mm to about 5 mm. Generally, the manufacturers of endoscopic accessories produce accessories having outer diameters which allow them to fit all the working channels. In particular, as regards the endoscopic injection needles, the outer diameter of catheter ranges from 1.9 mm to 2.3 mm; thus, considering that the inner injection tube is contained in the outer catheter, its internal diameter is usually 1 mm or less. Such a small diameter of the injection tube causes a high dynamic resistance to the flowing of the solution; this is more valid and important when a viscous solution is used. For this reason, the viscous solutions used for EMRs and ESDs often need to be diluted before their use to make the solutions able to flow through the injection needle, with a loss of their characteristics of providing a high and long-lasting cushion. WO2011/103245 A1 describes a kit and a method for delivering a injectable solution to a tissue treatment site, for use in ESD. Said kit includes a housing having a chamber, a proximal portion and a distal portion. An injectable solution having a viscosity greater than about 10000 cP is provided in the chamber. The kit also includes a plunger movably positionable within the proximal portion of the chamber, the plunger provides a seal at the proximal end portion. A pressure gauge is also provided with the kit. A handle is connected to the housing and a plunger advancing member having a plunger handle is connected thereto. The plunger advancing member is provided separate from the housing and includes a distal portion configured for operably connecting with the proximal portion of the housing. The kit also includes an inner shaft provided separate from the housing and having a proximal end portion configured for operably connecting with the distal portion of the housing for receiving the injectable solution there through and a distal end configured for insertion in to the tissue treatment site. As a skilled in the art would recognize, such a device allows the physician to apply a pressure much higher than using a normal syringe, thus allowing the high viscous solution, having a viscosity of 10000 cP or greater, to flow into the injection tube. Furthermore, WO2011/103245 A1 discloses that suitable materials for inclusion in the injectable solution include methylcelluloses, such as carboxymethyl cellulose (CMC) and hydroxypropyl methylcellulose (HPMC), extracellular matrix proteins, elastin, collagen, gelatin, fibrin, agarose, and alginate or mixtures thereof. However, the use of such a “high-pressure” generating device during the endoscopic examination is known for being not favourably accepted by the experts of the field, since it is cumbersome, additional work is required to put it in place, it is difficult to be operated therefore it represents a complication of the EMR and ESD procedures.
Another tentative to overcome these issues is described in WO2009/070793 A1 which discloses the use of purified inverse thermosensitive polymers in EMR. As well known in the art, inverse thermosensitive polymers are polymers which, upon dissolution in solvents (such as water) in a concentration above the critical micellar concentration (CMC), have the tendency to form micelles. At concentrations higher than the critical gelation concentration (CGC), these micelles can order into a lattice; the result is a solution which shows inverse characteristics of viscosity, which means that said solution displays an increase of its viscosity with the temperature. Eventually, when the temperature is raised above the critical gelation temperature (CGT), a gel forms. The gelation is due to physical entanglement and packing of the micellar structures, and it is reversible, thus the gel turns back to a liquid form when temperature is lowered below the critical gelation temperature. Polymers of this kind are well known in the art, and comprise, for examples, poloxamers (commercialized by BASF under the brand name of Kolliphor™) and poloxamines (commercialized by BASF under the brand name of Tetronic™). Aqueous solutions of those polymers at concentrations above CGC can be liquid at room temperature and can form a gel once heated up to body temperature (i.e. about 37° C.). WO2009/070793 A1 discloses the use of a composition comprising a purified inverse thermosensitive polymer in an endoscopic procedure for gastrointestinal mucosal resectioning. Said composition, called LeGoo-endo™, is an aqueous solution of purified poloxamer 237; it is disclosed that the rapid reversible liquid to gel transition achieved as a result its purified nature allows LeGoo-endo™ to be liquid at room temperature and to become a gel only as it emerges from the catheter at the EMR site, once heated to body temperature. WO2009/070793 A1 teaches that, in order to obtain said rapid liquid to gel transition, the use of a purified poloxamer was needed, and that said purified poloxamer was obtained by a purification process aimed to the obtainment of a purified polymer characterized by a lower polydipersity of the molecular weight. Moreover, WO2009/070793 A1 discloses that it was necessary to develop a method of injecting through a catheter into the intestine or stomach a purified inverse thermosensitive polymer solution that transitions to a gel at body temperature. Among the challenges overcome was the fact that because the catheter quickly reaches body temperature while resident inside the body, the purified inverse thermosensitive polymer could gel inside the catheter prior to reaching the desired site for EMR. WO2009/070793 A1 discloses that the delivery problems were solved with a system comprising a high-pressure needle catheter connected to a syringe filled with purified inverse thermosensitive polymer solution, wherein said high-pressure needle catheter was contained within an administration device (e.g., a syringe pump) that generated pressure on the plunger of the syringe through a manual (e.g., screw), electrical or pressurized-gas mechanism. As a matter of facts, in the in vivo example, WO 2009/070793 A1 discloses that five EMR were performed in the colon of 2 pigs with LeGoo-endo™ using a 23-gauge seletotherapy needle with a 5-mL syringe and a balloon dilator gun; LeGoo-endo™ was kept on ice during the intervention. Saline containing syringes were also kept on ice to cool the catheter immediately before poloxamer injections. As a person skilled in the art will recognize, the operating procedure disclosed by WO2009/070793 A1 is quite complex, for the following reasons: it requires that the purified inverse thermosensitive polymer solution is kept on ice during the intervention; it requires the use of a particular, high-pressure needle catheter; it requires that, immediately before the injection of the purified inverse thermosensitive polymer solution, the catheter is cooled by means of injections of cold normal saline solution kept on ice; it requires an administration device (e.g., a syringe pump) that generates pressure on the plunger of the syringe to administer the purified inverse thermosensitive polymer solution. U.S. Pat. No. 7,909,809 teaches a method for performing an interventional endoscopic procedure in the gastrointestinal tract such as polypectomy, endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD), said method comprising the administration to a human of a bulking or cushioning material that has characteristics of phase transition from a low viscosity state (e.g. liquid phase) into a high viscosity state (e.g. gel phase) in response to a predetermined temperature (e.g. body temperature).
As delineated above, an ideal composition for endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) has not yet been developed. As reported above, compositions in form of solution containing, for example, HA (hyaluronic acid) are known in the art: HA (hyaluronic acid) solutions are viscous and capable of providing long-lasting submucosal cushions; moreover, they are safe and non toxic. However, they are known to be highly expensive.
Cellulose derivatives, such as HPMC and CMC, are cheap and their solutions are capable of providing long-lasting submucosal cushions; however, due to their viscosity, a particular device such a syringe pump is required to make them flow into the injection needle, thus they are known for being difficult and uncomfortable to be injected.
Inverse thermosensitive polymers, such as poloxamers and poloxamines, are cheap and their solutions, in view of their capability of gelling at body temperature (i.e. about 37° C.), are capable of providing long-lasting submucosal cushions; it is however known in the art that, to obtain the gelification of the solution at body temperature (i.e. about 37° C.), such polymers need to be contained in the solution in a concentration equal to or above the critical gelation concentration (CGC), which is the concentration at which the transition of phase from solution to gel occurs upon heating at or above the critical gelation temperature (CGT). Accordingly, such polymers are usually contained in the known solutions in an amount equal to or above the critical gelation concentration (CGC). Similar concentrations of these polymers however cause several drawbacks, such as the gelification of the solution containing thereof inside the injection needle. A complex procedure is performed in order to avoid that the solution gelled inside the injection needle, namely keeping the composition on ice, cooling the injection needle with cold NS (normal saline solution) then using a syringe pump to administer them, with evident disadvantages for the endoscopist.
Therefore, there is the need to provide a composition for use in endoscopic procedure (particularly in EMR and ESD) able to be safe, inexpensive, non toxic, readily available, easy to inject and at the same time capable of providing a high, long-lasting submucosal cushion.